1. Field
The invention relates generally to tracking a location of an object, such as a tool, within an enclosed structure, such as a manufacturing facility.
2. Background
Tracking the location of a tool, such as drill or a torque tool, within a manufacturing facility can be of value for many reasons or purposes. For example, tracking the location of a tool used in the production of complex, high quality, high reliability, highly regulated parts can be of great value in assuring proper assembly. An example of such a tool might be a torque tool used to tighten the fasteners that hold the skin of an aircraft wing to the substructure. Aircraft assembly is highly regulated by the government with very strict quality and documentation requirements. Accordingly, assurances that the each nut, bolt, hole, rivet, etc. has been properly installed, in accordance with very tight specifications, must be satisfied and supporting documentation must be generated.
At least some known instrumented tools can record the data associated with the functionality of the tool, such as torque and number of rotations. However, such instrumented tools typically do not record or track positions or locations of the tool relative to the part being operated on by the tool, for example the aircraft wing skin and substructure. Information regarding the positions or locations of the tool relative the part being operated on can be very helpful in verifying performance of certain assembly operations. Generally, known indoor global positioning systems (GPS) systems can locate a sensor attached to the tool, but data processing limitations of the indoor GPS systems make them difficult to use for determining a particular feature, e.g., a hole or fastener, the tool is acting on, e.g. drilling or tightening. For such contemporary tool tracking systems to track specific features on which a tool is operating, a single sensor would have to be located at the point of interest on the tool, i.e., the part of the tool making contact with the particular feature. For example, the point of interest for a drill would be the tip of the drill bit. Having a sensor located at the point of interest on most tools would be impractical and render the tool unable to perform its intended function.
Two sensors can be attached collinearly with the point of interest on the tool, however, this can be cumbersome to implement in practice because it reduces flexibility of sensor placement. Additionally, indoor GPS typically involves the use of vector bars to define a point of space. However, to be useful for tracking the location of the tool's point of interest, the point of interest must be at the intersection of the vector bars. This requires specific placement of the sensor on the tool. But, with many tools such specific placement is not feasible due to the size, shape, weight or features of the tools.